1. Field of the Invention
The present invention relates generally to contact assemblies and, more particularly, to a clamp-jaw contact assembly, such as for a watt-hour meter socket. The invention also relates to meter sockets employing clamp-jaw contact assemblies.
2. Background Information
Watt-hour meters are typically used by electric utilities to measure electrical consumption in residential, commercial and industrial applications. To accommodate the watt-hour meter, equipment is provided with a watt-hour meter socket. Such a meter socket contains a plurality of xe2x80x9cmeter jawsxe2x80x9d to accept bayonet stabs or contacts on the base of the watt-hour meter.
Meter sockets having locking jaws for receiving the bayonet or blade contacts of a watt-hour meter are well known. See, for example, U.S. Pat. No. 3,281,550. Meter sockets are generally located in a rectangular enclosure having an opening in a top panel for receiving line cables and an opening in a bottom panel for receiving load cables. The meter socket is mounted to a back panel of the enclosure. A removable front panel has an opening for receiving the dome portion of the meter, which extends therethrough when coupled to the meter socket.
A typical residential meter socket is of the xe2x80x9cplug-in typexe2x80x9d in which the bayonet stabs on the meter are retained and clamped to corresponding meter jaws using the inherent spring pressure of the meter jaws. For some residential applications, and for the majority of commercial and industrial applications, a xe2x80x9cclamp-jawxe2x80x9d type of meter socket is employed. In the clamp-jaw type meter socket, the clamping force of the jaws upon the meter bayonets is enhanced by the addition of a spring, such as a straight beam spring or a coil spring.
In a typical construction, the meter jaw assembly includes a stationary jaw or contact, and a moveable or pivoting jaw or contact. The moveable jaw, with the aid of the aforementioned spring, exerts pressure on the corresponding meter bayonet, thereby clamping it to the stationary jaw.
U.S. Pat. No. 5,775,942 discloses a meter socket employing a plurality of jaw-type contact assemblies including a stationary contact, a moveable contact and a conductor terminal.
FIG. 1 shows a prior clamp-jaw assembly 2, which generally includes three component parts: a stationary contact 4 (as best shown in FIG. 2), a moveable contact 6 and a conductor terminal (not shown). The stationary contact 4 is preferably a one-piece construction including an elongated body 8 and a generally unshaped bottom portion 10 having a vertical extension member 12 and a conductor terminal interface 13. The elongated body 8 includes a pair of wings 14, which extend perpendicular to the elongated body 8. Preferably, the stationary contact 4 is stamped and bent into shape from a single piece of conductive metal, such as copper.
The moveable contact 6 is pivotably mounted to the stationary contact 4 by a pivot pin 16. The moveable contact 6 is also preferably a one-piece construction. The moveable contact 6 includes a back portion 18 having a pair of wings 20 (only one of the wings 20 is shown) extending substantially perpendicular to the back portion 18. A low portion 22 of the moveable contact 6 is bent for receiving a biasing mechanism, such as a spring 24, to bias a portion 26 of the moveable contact 6 to be in a clamped position with respect to the elongated body 8 of the stationary contact 4.
Known technology for jaw-type contact assemblies typically employs both a spring and a separate machine driven tubular steel rivet to accomplish the respective clamping and pivoting actions. However, the rivet must be installed by a rivet setting machine or else staked manually, in order to retain the rivet in the jaw-type contact assembly. Also, a beam spring or coil spring is separately installed in that assembly in order to provide the desired clamping force.
There is room for improvement in clamp-jaw contact assemblies.
There is also room for improvement in watt-hour meter sockets and in meter socket clamp-jaw contact assemblies.
These needs and others are met by the present invention, which combines both spring clamping force and pivot functions in a unitary spring/pivot member, which may be assembled in a meter socket clamp-jaw contact assembly without the need for a machine operation.
As one aspect of the invention, a clamp-jaw contact assembly comprises: a stationary contact adapted to engage a meter socket cavity; a moveable contact adapted to engage a meter bayonet; and a unitary member pivotally mounting the moveable contact to the stationary contact and adapted to bias the moveable contact toward the stationary contact.
The unitary member may be a U-shaped wire-form or a wire-formed member.
The unitary member may be a spring/pivot member having a rectangular shape with a pair of ends and an open portion therebetween.
The stationary contact may include an elongated body and a pair of sides, which extend from the elongated body; the moveable contact may include a body portion and a pair of sides, which extend from the body portion; the sides of the stationary contact and the moveable contact may have openings; the unitary member may be a spring/pivot member having a first end, which passes through a first pair of the openings of a first pair of the sides of the stationary contact and the moveable contact; and the spring/pivot member may have a second end, which passes through a second pair of the openings of a second pair of the sides of the stationary contact and the moveable contact.
The unitary member may be a spring/pivot member having a first end, a second end and an opening therebetween; the stationary contact may include first and second openings; the moveable contact may include first and second openings; the first end of the spring/pivot member may engage the first openings of the stationary contact and the moveable contact; and the second end of the spring/pivot member may engage the second openings of the stationary contact and the moveable contact.
The unitary member may be a spring/pivot member having a general U-shape including a pair of ends disposed from a pair of sides disposed from a bias member, with the pair of ends pivotally mounting the moveable contact to the stationary contact. The stationary contact may include a surface. The moveable contact may include a first portion, which is pivotally mounted to the stationary contact, and a second portion proximate the surface of the stationary contact and adapted to be biased by the bias member of the spring/pivot member.
The stationary contact may be elongated and include a pair of protrusions. The sides of the spring/pivot member may engage the protrusions of the stationary contact. The moveable contact may pivot about the ends of the spring/ pivot member. The second side of the second portion of the moveable contact may engage the bias member of the spring/pivot member, in order to maintain the moveable contact in a clamped position with respect to the stationary contact.
As another aspect of the invention, a meter socket clamp-jaw contact assembly comprises: a stationary contact; a moveable contact; and a unitary spring/ pivot member pivotally mounting the moveable contact to the stationary contact and adapted to bias the moveable contact toward the stationary contact.
As another aspect of the invention, a meter socket comprises: a socket block including a plurality of cavities recessed therein; and a plurality of clamp-jaw contact assemblies mounted in the cavities of the socket block, each of the contact assemblies comprising: a stationary contact engaging a corresponding one of the cavities; a moveable contact adapted to engage a meter bayonet; and a unitary member pivotally mounting the moveable contact to the stationary contact and adapted to bias the moveable contact toward the stationary contact